Eladia Peña-méndez - Academia.edu (original) (raw)

Papers by Eladia Peña-méndez

Chemosphere, May 1, 2016

Silver nanoparticles (AgNP) are emerging pollutants. The use of novel materials such as Cu-(benze... more Silver nanoparticles (AgNP) are emerging pollutants. The use of novel materials such as Cu-(benzene 1,3,5-tricarboxylate, BTC) Metal-Organic Framework (MOFs), for AgNP adsorption and their removal from aqueous solutions has been studied. The effect of different parameters was followed and isotherm model was suggested. MOFs adsorbed fast and efficiently AgNP in the range C0 &amp;amp;amp;lt; 10 mg L(-1), being Freundlich isotherm (R = 0.993) these data fitted to. Among studied parameters a remarkable effect of chloride on sorption was found, thus their possible interactions were considered. The high adsorption efficiency of AgNP was achieved and it was found to be very fast. The feasibility of adsorption on Cu-(BTC) was proved in spiked waters. The results showed the potential interest of new material as adsorbent for removing AgNP from environment.

Journal of Capillary Electrophoresis, 1998

Frontiers in Medicine, Apr 1, 2021

ACS Chemical Neuroscience, Dec 30, 2022

European Food Research and Technology, May 1, 2004

Scientific Reports, Feb 25, 2021

Social Science Research Network, 2021

A new Cotton@Fe-BTC composite formed by Fe-BTC (BTC-H3 : trimesic acid) metal framework (Fe-BTC M... more A new Cotton@Fe-BTC composite formed by Fe-BTC (BTC-H3 : trimesic acid) metal framework (Fe-BTC MOF loading as high 38 wt %) supported by cellulose fibre is synthesised in aqueous media using a simple and green preparation method, described for the first time in this manuscript. This new strategy relies on the synergetic effect of the pure cellulose and MOFs frameworks resulting in hybrid nanofibers of MOFs@cellulose composite. A complete characterization of the composite material reveals its structural similarity to MIL-100(Fe), a Fe-BTC material. The Cotton@Fe-BTC composite potential use as an eco-friendly and low-cost adsorbent was evaluated for its adsorptive performance for the removal of dyes belonging to the triarylmethane dye family (Malachite Green (MQ), Brilliant Green (BG), Pararosaniline (PR), Basic Fuchsine (BF), Crystal Violet (CV), Methyl Green (Met-G), Victoria Blue B (VB), Acid Fuchsin (AF) and Aniline Blue (AB)) in aqueous solution. The fast kinetics and high dye removal efficiencies ( > 90%) obtained in aqueous solutions. The structure of Cotton@Fe-BTC netwok, contributed to the remarkable adsorption properties towards a variety of triphenylmethanedyes. The interparticle studies showed two main steps in the dye’s adsorption processes, with the exception of AF and BG. The equilibrium adsorption capacities qe (mg/g) follow the order: AF (3.64) < Met-G (3.70) < AB (4.87) < PR (5.52) < BF (5.76) < Met-G (7.22) < CV (9.63) < BG (16.34). However, going insight the adsorption mechanisms, it was remarkable the finding that the reaction paths taking into account the influence of water molecules on the anionic dye adsorption, through the so-called solvation/desolvation penalty processes, may not be ignored. The easy preparation and manipulation of Cotton@Fe-BTC network as well as its stability and excellent performance for the adsorption makes this material a good candidate for a broad range of applications.

Journal of Agricultural and Food Chemistry, 2010

Bioorganic Chemistry, Feb 1, 2021

Environmental Nanotechnology, Monitoring and Management, Dec 1, 2021

Abstract The direct synthesis of nano-{Fe-BTC} MOFs was performed following green chemistry rules... more Abstract The direct synthesis of nano-{Fe-BTC} MOFs was performed following green chemistry rules. This nanomaterial has been characterized by several techniques showing structural similarities with commercial Fe-BTC MOFs, although it has greater porosity due to the presence of mesopores and micropores, that can make it an efficient adsorbent for fluorescent anionic dyes through electrostatic and π-π interactions between dye and nano-{Fe-BTC}. The adsorption isotherms fit the Freundlich model: tetrabromo-fluorescein(Br-FL) has the highest KF value, followed by dichloro-fluorescein(Cl-FL) and fluorescein(FL). The kinetic study suggests that the adsorption onto nano-{Fe-BTC} follows the pseudo-second-order model and the adsorption capacities follow the order Br-FL (qe 0.836 mg·g−1) > FL (qe 0.106 mg·g−1) ~Cl-FL (qe 0.100 mg·g−1), pH = 4. The use of methanol (5% NH3) allows recoveries of the dyes from nano-{Fe-BTC} ranging from 90% to100%. The presence of inorganic ions and organic substances in the water solution does not affect the adsorption of the dyes even when possible interfering species were present at concentrations that were up to 109 times higher than that of the dyes. The method was successfully applied to remove the target dyes from spiked water samples, showing the potential of high porous nano-{Fe-BTC} MOFs as a promising adsorbent for the effective removal of dyes from waters.

IntechOpen eBooks, Jun 2, 2021

Heliyon, Dec 1, 2021

a Departamento de Química. Unidad Departamental de Química Analítica, Facultad de Ciencias, Unive... more a Departamento de Química. Unidad Departamental de Química Analítica, Facultad de Ciencias, Universidad de La Laguna, Tenerife, Spain. b Inorganic Chemistry Area, Section of Chemistry Faculty of Science; Instituto Universitario de BioOrgánica “Antonio González”, University of La Laguna, Tenerife, Spain. c Department de Química. Facultat de Ciències, Universitat de Girona, C/ Ma Aurèlia Capmany, 69, 17003 Girona, Spain d Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5/A14, 625 00 Brno, Czech Republic.

ABSTRACT Capillary zone electrophoresis (CZE) was used for the separation of humic acids. The inf... more ABSTRACT Capillary zone electrophoresis (CZE) was used for the separation of humic acids. The influence of the buffer solution on the separation of a commercial humic acid was studied. The use of an 8 mmol l−1 HCl-59.8 mmol l−1l-alanine buffer (pH 3.17) leads to the separation of humic acids into two fractions. The composition and pH of this buffer and some instrumental parameters such as voltage, injection volume and wavelength of detection were optimized and the quality parameters of the method were determined. Two further commercial humic acids were assayed. The one that showed the highest peak signal was used as a reference for the rough quantification of the others.

This contribution presents a comparative study of the use of PLS and ANNs to analyze A and C mixt... more This contribution presents a comparative study of the use of PLS and ANNs to analyze A and C mixtures using UV-Vis derivative spectra. The optimum ANN architecture enabling to model the system was established by means of TRAJAN 6.0 program. Several algorithms (Back propagation, Conjugate gradients, Quick propagation, and Delta-Bar Delta algorithm) were used for the training of the ANN to obtain a reliable model. With help of a suitable experimental design in combination with soft ANN modelling, the concentration of both A and C in mixtures can be quantified with an excellent accuracy (about 1 %). The quality of the testing set was evaluated on the basis of the average root mean square error for prediction (RMSEP) calculated from true and found values of A and C concentrations (RMSEP = 0.07 for A and 0.09 for C). It was found that ANN gives better results for the first and second derivative spectra than for original spectra. Furthermore, in comparison with PLS the ANN provides a more reliable and precise approach in the multicomponent analysis of A and C mixtures, where a number of different interactions take place.

The chemistry of gold nanoparticles (GNPs) represents fascinating interdisciplinary field of rese... more The chemistry of gold nanoparticles (GNPs) represents fascinating interdisciplinary field of research with applications in physics, chemistry, nanotechnology, and medicine, especially. GNPs are also used for the synthesis of novel nano-structured materials such as nanocomposites with graphene, carbon nano-tubes and/or fullerenes. Nanodiamonds (NDs) show unique mechanical, thermal and electrical properties which make them promising molecular building blocks in nanotechnology. Because of their biocompatibility and non-toxicity [1], NDs are used as drug carriers and building blocks e.g., for the fabrication of tissue scaffolds and surgical implants, etc. Metal carbides are extensively applied in industry. For a long time it was believed that gold is not forming carbides. Matthew in 1900 reported for the first time gold carbide (Au2C2) [2]. The formation of gold carbides via laser ablation synthesis was preliminarily indicated in our laboratory [3, 4]. Nowadays, it is known that i) gold forms not only carbides but also aurides and ii) gold-carbon interaction is important for development of electronic devices. The aim of this work is to study the formation of gold carbides via laser ablation synthesis (LAS) using as a precursor a kind of nanocomposite of GNPs with NDs. The GNPs-NDs nanocomposite (Fig. 1 a) was prepared and characterized by atomic force and transmission electron microscopy, energy dispersive X-ray spectroscopy and mass spectrometry. Laser ablation synthesis of gold carbides (Fig. 2) was carried out by laser desorption ionisation time-of-flight mass spectrometry (LDI-TOF-MS). Example of mass spectrum indicating the formation of singly charged AumCn+ clusters is given in Fig. 1 b. Gold carbides AuCn+ (n = 1-11), Au2Cn+ (n = 1-16) and Au3Cn+ (n = 1-10) and also some gold aurides were observed. The structure of observed AumCn clusters most probably corresponds to gold carbides, but also endohedral supramolecular complex formation, e.g., Au@C10 is not excluded (Fig. 3) [5]. Such possibility was supported by modelling via semi-empirical approach using the HYPERCHEMTM program (release 5.1, 1998) from Hyper-cube Inc. (Gainesville, FL, USA). The confirmation of diamond doped structure with gold atom would mean the first experimental evidence of gold-doped NDs. Concluding, laser ablation of GNPs-NDs nanocomposite leads to synthesis of Au-C clusters. Stoichiometry of altogether 37 gold carbides was established while also some gold aurides were formed probably from partially hydrogenated NDs. It is suggested that some “gold carbides” might be gold-modified diamonds or gold-diamond endohedral complexes. Results concerning the synthesis via laser ablation might initiate development of new Au-C materials with specific properties.

Using PCA and CA humic acids can be classified and differences in Antarctica samples from the oth... more Using PCA and CA humic acids can be classified and differences in Antarctica samples from the others can be seen.

Supramolecular chemistry deals with the study of organized molecular systems in which the molecul... more Supramolecular chemistry deals with the study of organized molecular systems in which the molecules or ions are held together by non-covalent interactions [1, 2, 3]. The reversibility of such interactions makes supramolecular “dynamic” systems. This is the key principle on which the design of new molecular machines is based. Examples are given in Fig. 1-2.Also, the labile interactions between particular molecules and drug molecule are the way to develop new drug carriers which is nowadays topic of a high importance in medicine. The formation of supramolecular complexes is usually assisted by carrying out their synthesis preparing sufficient amount of the products and examining them by nuclear magnetic resonance (NMR) or other classical analytical techniques. This can be tedious and laborious process and might require rather high quantity of the reagents. Matrix Assisted Laser Desorption Ionisation (MALDI) and/or Surface Assisted Laser Desorption Ionisation (SALDI) Time Of Flight (TOF) mass spectrometry are traditionally used in Proteomics and Bio-Analytics. We have applied MALDI and SALDI for the fast screening to find out the formation of supramolecular complexes and/or to search for drug carriers. For this purpose, mass spectrometric analysis was used in combination with combinatorial experiments mixing the reactants, either in aqueous or organic phase and the products were then examined. Reactions can also be done directly on a MS target. In some cases, experimental design (ED) was also used in order to reduce the number of combinatorial experiments. In this work several examples of supramolecular complex formation using as hosts cyclic ethers, cyclodextrines, cucurbit[n]urils etc., and as guests fullerenes, nanoparticles, or drugs like antivirals, cisplatin, etc., will be given and discussed. The advantage is that the experiments can be done using minimal amount of the chemicals (such as 10-5 moles or less) which is important for scarce or expensive substances and materials. The proposed application of MALDI and SALDI TOF mass spectrometry with ED represents an efficient and economic way to search for the formation of new supramolecular complexes and/or for possible drug carriers.